Climbers who were on the mountain when a mixture of ash and lava streamed out have come down safely, according to Japanese media which cited local police.
The Japan Meteorological Agency, which raised the alert level for the volcano to 3 on a scale of 5, flagged a risk of falling rocks and pyroclastic flows around the crater â one of the worldâs largest.
The wind could blow volcanic rocks far around the mountain, posing a threat along with ash, an official from the agency, Ozaki Tomoaki, told reporters. âDo not enter dangerous areas,â he added.
Smoke engulfed the mountain, where a thick cloud of ash towered over the mouth of the volcano, footage on the countryâs public broadcaster NHK showed. Rocks flew more than half a mile to the south, it said.
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